1. Technical Field
The present invention relates generally to a clutch for transmitting torque between an input and an output, and more particularly to a clutch for transmitting torque in one direction but not in the other.
2. Background Art
As such, a one-way clutch is well known in the art and is utilized for electric power steering in motor vehicles, for example. This clutch is disposed between an electric motor and a steering shaft to connect therebetween for transmitting torque in one particular state, but not in another. A clutch cam is inserted into a large cylindrical portion of the clutch via rollers. By pressing the rollers against the large cylindrical portion by the clutch cam, relative rotation between the large cylindrical portion and the clutch cam is stopped to allow torque to be transmitted.
However, in such a clutch, since the compression of the rollers against the clutch cam causes torque to be transmitted, malfunctions tend to occur because the rollers are put between the clutch cam and the large cylindrical portion.
Additionally, a one-way clutch is well know in the art which includes two rotatable members, as input and output shafts, mounted for rotation relative to each other and a coil spring wound across the rotatable members. When the coil spring is put around the rotatable members tightly, the rotatable members rotate simultaneously with each other to transmit torque therebetween. When tight winding across the members is not provided, skidding occurs between the rotatable members and torque is not transmitted.
In a conventional clutch of this type, when no torque is being transmitted, friction occurs due to contact between the inner peripheral surface of the coil spring and the outer peripheral surfaces of the rotating members. As a result, even when the clutch is disengaged, torque due to friction is still present.
Other one-way clutches are therefore sought, and it is to this end that the present invention is directed.